The present invention relates generally to folding wing structures for airborne vehicles such as missiles and the like.
Many rockets and missiles utilize some form of wing or stabilizer structure for stabilizing and guiding the airframe during flight. Missiles are frequently stored and launched from tubular launchers, and may be deployed from aircraft, ships or land vehicles, where storage space is limited. Under such circumstances it is necessary to minimize the space required for storage of the missile prior to launch, and fixed wings substantially increase the storage space requirements.
In view of this, various folding or collapsible wing structures have been proposed in the past for missiles and rockets, which are initially collapsed into a storage position in which they are substantially flush with the missile body, and which can be erected automatically during flight of the missile to swing out from the missile body. In U.S. Pat. No. 4,351,499 of Maudal et al., which is
assigned to the same assignee as the present application, for example, a retractable, self erecting wing for a missile is described, which comprises a double walled flexible fabric body held in an extended position by spring loaded struts. The wing is folded into a slot in the outer wall of the missile. A simi)ar structure is shown in U.S. Pat. No. 4,586,680 of DiTommaso et al., also assigned to the same assignee as this application. In this case the strut assembly supporting the double walled wing comprises a leading and a trailing strut each comprising a telescoping upper and lower tubular member each pivoted at their lower ends to a support structure and pivoted together at their upper ends to form a triangular structure when fully erect. Compression springs within the struts force them towards their fully extended position. Locking tabs are provided to resist collapse of the tubular members when erect.
It has been found that these previous structures have the capability to deploy and provide aerodynamic lifting surfaces at air speeds up to around Mach 0.2 at sea level. The double walled fabric wing encloses an air pocket which acts as a damper to resist wing flutter. However, at speeds above Mach 0.2, the ability of the wing to erect is limited because of inadequate erecting force and also because of severe fabric flutter during the erection process. If the wing is successfully erected, the locking mechanism may provide inadequate structural strength at very high speeds, and the fabric flutter at such speeds may over stress, heat and destroy the fabric of the wing, particularly at angles of attack at and around zero. Thus the wing is liable to disintegrate at speeds above Mach 0.2.